Inert ammunition filler composition comprising an alum



United States Patent ABSTRACT OF THE DISCLOSURE Dimensionally stable inert practice ammunition fillers which are compatible with high explosives, comprising, in the main, alums combined with cellulose or dextrin :to lower the overall specific. gravity of the alumn combination, and with BaSO, or Fe O to raise the overall specific gravity of the alum combination.

This invention relates to new compositions. of matter and more particularly concerns practice ammunition having improved inert fillers which provide excellent dimensional stability characteristics.

Prior art practice ammunition generally contain a wax or other organic material such as polychlornaphthalene or castorwax which are non-crystalline, soften long before melting and expand and contract extensively with changes in temperature. Poor dimensional stabilityand strength characterize these waxes or organic compounds. Further,

their coetficients of thermal expansion are such that, upon cooling, the filler material shrinks from the shell..walls and provide a loose charge having poor and non-reproducible ballistic properties. Additionally, polychlornaphthale-ne based filler materials are toxic in nature.

In bombs, shells, and the like, usedfor practice ammunition, high explosive charges are replaced-by an inert material which duplicates the weight of the explosive. In addition to having the proper weight for the volume oecupied, the inert material should be capable of being 7 loaded in-the same manner and, desirably, with. the same equipment used for explosives. In orderto meetthese requirements, the material should melt between 75 and 100 C. Furthermore,.to permit reuse of the metal parts, the inert filler must be amenable to ready removal by washing with steam or hot water. The filler material should form a homogeneous mass upon cooling which will be free of voids, and yet readily admit of composition variations such that desired specific gravities from about 1.4 to 2.0 can easily and economically be attained. Most importantg-the inert material must have dimensional staquantities will be used. Finally, the filler material should 1 be non-toxic, odorless, and compatiblle with such wellknown high explosives as RDX (cyclotrimethylenetrinitramine), HMX (cycletetramethylenetetranitramine) and TNT (2,4,6-trinitrotoluene It is, therefore, the principal object of this invention to provide compositions of matter having the aforementioned advantages.

Another object of the invention is to provide inert fillers for practice ammunition having the aforementioned advantages.

Other objects and fetaures of the invention will become apparent as the invention is more fully hereinafter disclosed.

In accordance with these objects, it has been discovered that certain inorganic compounds, such as alums, will combine with cellulose, to yield an inert filler having a lower specific gravity than the alum, or with BaSQ; to yield an inert filler having a higher specific gravity than the alum, and yet fulfilling the advantages contemplated by the invention.

The following table illustrates the variations and compositions required to produce a specific gravity range that will be characteristic of a variety of explosives:

TABLE I.PERCENTAGES OF INERT FILLER FOR YARYING SPECIFIC GBAVITIES Composition, Wt. Percent AlNH4( SO 4)2 l2H2O' Cellulose Specific Gravity BaSO4 If desired, greater ranges or intermediate values readily. be obtained by'one skilled in the art by -varyin g the percentages above.

The. ammonium alum is preferably rice to nut size and will have a melting point of ab'0ut'9 3.5 C. cellulose is a powdered, purified, wood type having a moisture con- I AlK SQ 1 2H O is somewhatinferior to ammonium alum because the specifiqgrayity is slightly less representative of explosives contemplated by this invention.

In lieu of cellulose, dextrin may be used advantageously ,to .yield an inert filler having a lower specificgravity than .the an1rnouium -alum and Fe O may replaceBaSO to provide an,inert filler having'a higher specific gravity than .theammoniumalum.

In those instances where anundesirable. chemical reactionmay occur between the reactantsfand the cartridge casing, a corrosion. inhibitor such as. thiourea octadecyh amine,- polyethanol rosinamine D, and the like,j may be incorporated with,-the react'ant s in a proportion of jabout 0.5 to 1.0 parts inhibitor to parts of ammoniumalum units substitute.

Since certain applications for inert filler require contact with explosives, compatibility tests were conducted with many of the most widely and frequently used types. I have determined that any explosive based on TNT, RDX, or HMX may satisfactorily and safely be used in contact with my inert filler.

In the preparation of my inventive inert fillers, the ammonium alum will be melted by heating to about 100 C. in a stainless steel, glass, copper or other suitable vessel fitted with a mixer. If a stainless steel kettle is used for melting and mixing, a solution containing one part CuSO -5H O in four to six parts water for each 100 parts of ammonium alum must be used. Apply heat, by any suitable means, to the kettle containing the solution, start the mixer, and allow the inside walls of the kettle to be wetted with the solution. If glass, plastic, copper, or leadused unless they are coated with a paint free from iron oxide, zinc oxide or aluminum. Throughout the melting and mixing, the kettle should be opened only while material is being added in order to minimize evaporation of I thes-team that is evolved.

Now add the desired weight of alum, or its substitute, rather slowly to the heated kettle containing the copper sulfate solution so that the mixer will not become overloaded. When all the alum hasbeen added, continue the heating and stirring in the closed vessel until a clear liquid is obtained. Open the kettle, add'the cellulose or barium sulfate as rapidly as possible, again close the opening and continue mixing until. a uniform dispersion appears to be obtained. Generally, this will require not more than five minutes. Add the required weight of corrosion inhibitor, if necessary, replace the cover and mix for two to three minutes. The temperature, of the mixture should be about 95 C.

Pour the mixture into shells or bombs which have previously been coated on their inner surfaces with an acid proof black paint or some other suitable coating which will prevent reaction of the molten mixture with the cartridge casing. Finally, allow the mixture to cool slowly to room temperature.

It is apparent from the foregoing description that I have provided new compositions of matter ideally suited for inert fillers for use inpractice ammunition, the inert filler being dimensionallystable over a wide range of tem-' perature, low in cost, non-toxic, odorless, water soluble and compatible with HMX, RDX and TNT. The specific gravity of the filler can be readily adjusted to simulate any explosive composition. Existingmelting and cast loading equipment may still be used. Rapid solidification with low shrinkage expedites the filling of bombs and shells. The'low viscosity of'the molten filler assures complete conformity to the shape of the container into which it is poured and the dimensional stability characteristicsof my composition assures adhesion to the walls of the article or container within a temperature range of about 70 to 190 F. Clean-up and disposal of excess filler is simple and rapid since it can readily be dissolved and be washed away with hot water or steam.

My compositions are expected to lend themselves-to other applications, such, for example, as in ballasts, molds and models wherein a hard, castable, dimensionally stable, inexpensive material of varying densities and colors might be desired. g

I claim:

1. A practice ammunition filler of a substantially inert composition of matter dimensionally stable over a temperature range of about 70'- to 190 F. and capable 4 composition having a specific gravity of about 1.58 a d comprising about 95 weight percent AlNH (SO -12H O and about 5 weight percent of cellulose.

3. An inert composition 'as described in claim 1, said composition having a specific gravity of about 1.50 and comprising about 90 weight percent of and about percent cellulose.

4. An'inert composition as described in claim 1, said composition having a specific'gravity of 1.71 and. mprising about 90 weight percent of AlNH (SO -12H O and about 10 weight percent barium sulfate.

5. An inert composition as described in claim 1, said composition having a specific gravity of about 1.77 and comprising about 85 weight percent of V and about 15 weight percent barium sulfate.

of yielding specific gravities within limits of about 1.50

6. An inert composition as described in claim 1, said composition having a specific gravity of about 1.85 and comprising about Weight percent of .AH HqISClQQ 121120 and about 20 weight percent barium sulfate.

7. An inert composition as described in claim 1, said composition having a specific gravity of about 1.95 and comprising about 75 percent by weight of AINH (SO 2 lZH O and about 25 weight percent barium sulfate.

.8; A practice ammunition filler of a substantially inert composition of matter dimensionally stable over a temperature 'range of about 70 to F. and capable of yielding specific gravities within limits of about 1.50 to 1.95, said composition comprising:

an inorganic compound selected from the group con- '-sisting of AlNH (SO 121-1 0, AlK(SO 121-1 0,.

. References Cited UNITED STATES PATENTS' 3,018,203. .1/1962 Guth 149-45 X 3,108,917 10/1963 McIrvine 149. -10s X CARL D. QUARFORTH, Primary Examiner.

BENJAMIN R. PADGETT, Examiner.

S. I. LECHERT, JR., Assistant Examiner. 

